How to register for Intellipoker (through PokerStars client):
http://www.intellipoker.com/articleshow.php?id=612

Basically it says that while logged in to PokerStars in the help menu there should be a signup option. It could be that it's only available under German language, but you could just change your language to German while doing it maybe?

When going through the registration you have to enter and confirm your password for the Intellipoker site (use a different one, obviously) - when registration is complete you should be able to log on to the Intellipoker site.

The basic reasoning behind the IntellPoker logo is advertising - they are paying players a number of IPP (Intelli Poker Points) for using the logo as avatars. A brief glance at the whole thing suggests that they don't even give you the logo so you configure it yourself. Rather they get the logo set up 'correctly' (no wrong zoom or colours or any such thing) by PokerStars when you sign up for the advertising deal on the Intellpoker site.

http://www.intellipoker.com/articleshow.php?id=1953
Hier Registrieren: - click 'Anmelden' (sign up). If playing cash games you'll be earning 4 IPPs per day!

Beyond this you're on your own. I'm just giving it a quick glance from work.